Identification of drought-responsive microRNAs in Medicago truncatula by genome-wide high-throughput sequencing.

Tianzuo Wang,Lei Chen,Mingui Zhao,Wen-Hao Zhang,Qiuying Tian

doi:10.1186/1471-2164-12-367

Abstract

BackgroundMicroRNAs (miRNAs) are small, endogenous RNAs that play important regulatory roles in development and stress response in plants by negatively affecting gene expression post-transcriptionally. Identification of miRNAs at the global genome-level by high-throughout sequencing is essential to functionally characterize miRNAs in plants. Drought is one of the common environmental stresses limiting plant growth and development. To understand the role of miRNAs in response of plants to drought stress, drought-responsive miRNAs were identified by high-throughput sequencing in a legume model plant, Medicago truncatula.ResultsTwo hundreds eighty three and 293 known miRNAs were identified from the control and drought stress libraries, respectively. In addition, 238 potential candidate miRNAs were identified, and among them 14 new miRNAs and 15 new members of known miRNA families whose complementary miRNA*s were also detected. Both high-throughput sequencing and RT-qPCR confirmed that 22 members of 4 miRNA families were up-regulated and 10 members of 6 miRNA families were down-regulated in response to drought stress. Among the 29 new miRNAs/new members of known miRNA families, 8 miRNAs were responsive to drought stress with both 4 miRNAs being up- and down-regulated, respectively. The known and predicted targets of the drought-responsive miRNAs were found to be involved in diverse cellular processes in plants, including development, transcription, protein degradation, detoxification, nutrient status and cross adaptation.ConclusionsWe identified 32 known members of 10 miRNA families and 8 new miRNAs/new members of known miRNA families that were responsive to drought stress by high-throughput sequencing of small RNAs from M. truncatula. These findings are of importance for our understanding of the roles played by miRNAs in response of plants to abiotic stress in general and drought stress in particular.

Highlights

MicroRNAs are small, endogenous RNAs that play important regulatory roles in development and stress response in plants by negatively affecting gene expression post-transcriptionally
High-throughput sequencing of small RNAs from M. truncatula Two sRNA libraries in which M. truncatula seedlings were treated with drought stress (DS) and without stress, control (CK) constructed from shoots of seedlings grown under the two treatment-regimes were sequenced by an IlluminaSolexa sequencer
We obtained a total of 13,683,619 reads from two small RNA libraries of M. truncatula by high-throughput sequencing

Summary

Introduction

MicroRNAs (miRNAs) are small, endogenous RNAs that play important regulatory roles in development and stress response in plants by negatively affecting gene expression post-transcriptionally. Recent studies revealed that miRNAs are involved in responses of plants to various abiotic and biotic stresses These include drought [14,15,16,17,18], cold [19,20,21], salinity [22], nutrient starvation [23,24,25,26], oxidative stress [27], submergence [28], UV-B radiation [29,30] and virus [31,32]

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Discussion

Conclusion